["Population and Development Review, EarlyView. ", "\nAbstract\nThe concept of super‐diversity posits that waves of immigration over several decades expand population heterogeneity on multiple social, demographic, economic, political, and legal dimensions, creating a mosaic of social and cultural life in immigrant‐rich spaces. This concept raises important demographic and sociological questions as to how this has happened, particularly in view of the long history of assimilation and integration theories, in which immigrant groups are hypothesized to become more similar to host society populations over time. In this study, we provide a demographic perspective, positioning immigration and integration as forces that influence population heterogeneity. We utilize a detailed dataset of population stocks and flows between 2011 and 2021 from Australia and develop a multiregional demographic model to quantify the contributions of immigration and integration to contemporary diversity. The results show how immigration drives diversification, giving rise to migrant and multidimensional diversity. Integration in terms of citizenship, language proficiency, occupational attainment, and homeownership is strongly evidenced and helps to shift the socioeconomic characteristics of foreign‐born populations and their children, though they do not have substantial impacts on measures of population diversity. These findings provide insights for theorizing and measuring the relationships between immigration and diversity, and their long‐term societal implications.\n"]